Fourdrinier machine

Langsieb, n. (Paper) endless wire, Fourdrinier web. -maschine, /. (Paper) Fourdrinier machine. 

Only handmade single sheets of paper were fabricated until, in 1798, a machine that could make continuous rolls of paper was invented in France. This machine consisted of a conveyor belt submerged at one end in a vat of suspended cellulose fibers. The conveyor belt was a screen so that water would drain from it as fibers were pulled out of the suspension. The entangled fibers were then squeezed through a series of rollers to create a long continuous sheet of paper. Within a few years, an improved version of this machine that used heated rollers was produced in England. The improved machine was called the Fourdrinier, after a wealthy industrialist who financed its creation. Automated Fourdrinier machines, such as the one shown in Figure 18.2, are still used today. 

What is a Fourdrinier machine, and what was the impact of its invention ... 

Fig. 1. Fourdrinier machine for producing printing-grade paper. iBeloit Corporation)...

Although the Fourdrinier machine is used for making almost all grades of paper and board, other designs are sometimes more advantageous. The cylinder machine, invented at about the same time as the Fourdrinier, consists of a rotating cylindrical mold covered with a wire screen and partially submerged in a vat. The stock flows into the vat, and a mat is formed on the cylinder under a hydraulic head difference between the stock level in the vat and the white-water level inside the cylinder. The... 

Paper machine Machine on which paper or paperboard is manufactured. The most common type is the fourdrinier machine using the fourdrinier wire as a felting medium for the fibers. 

The section of the paper machine where the paper is formed is referred to as the wet end. The fourdrinier machine is characterized by a... 

Paper is made by slurrying cellulose fibers at a very low concentration and filtering off most of the water on the moving wire screen of a Fourdrinier machine. 

The machine that converts the pulp into paper is called a fourdrinier machine, after Henry and Sealy Fourdrinier who financed its development in England in the early 1800s. The fourdrinier machine takes pulp that is still 99% water and converts it into a continuous web of paper containing only a small amount of moisture. 

Pulp is continuously fed into the fourdrinier machine on the surface of a moving endless belt of fine mesh screening, usually made of nylon. Deckle straps prevent the liquid pulp from slopping over the sides. The screening is shaken from side to side as it moves forward to help drain the water. Suction boxes below the screening pull more water through, as a wire-mesh-covered cylinder presses on the web of pulp from above. The cylinder may be covered with a plain wire cloth to impart a wove effect, or with wire in a ladder pattern to produce a laid effect. To produce a watermark, the paper-maker attaches a wire design to the cylinder. 

Like most fabrics, paper has a right and wrong side. The bottom of the web (called the wire side) next to the screening at the wet end of the fourdrinier machine is slightly rougher than the top (or felt) side. If only one side of the p er is to be used, the smoother side is usually chosen. Paper made on a twin-wire fourdrinier machine has either two felt sides or two wire sides this is because two webs of pulp are laid down simultaneously and pressed together as the paper is dried and finished. One-sided paper is more expensive than ordinary two-sided paper. 

Fourdrinier machine—The machine that forms paper from pulp, named after the English family that financed its development in the early 1 800s. Furnish—Specific combination of pulp and other ingredients used to make a particular kind of paper. Kraft process—process in which sodium sulfate is reduced by heating with carbonaceous matter in a furnace to form sodium sulfide, which is then used in a water solution with sodium hydroxide as a cooking liquor. The wood pulp is then cooked under pressure and at high temperatures. The kraft process, also known as the sulfate process, has a less corrosive influence on iron and steel than the sulfite process. 

Centrifugal Former. The use of a centrifugal former allows for the preparation of a sheet of paper that posseses a fiber orientation similar to the orientation present in commercial papers. With this apparatus, the fiber suspension is sprayed onto a fast rotating screen. The dynamic motion of the screen mimics the moving wire of the Fourdrinier machine and induces fiber orientation. In addition, by independently varying the flow of the fiber suspension and the speed of rotation of the screen, different degrees of fiber orientation can be obtained. 

One of the different types of machine used at present for making board is the vat or cylinder machine. The machine starts at the wet end (IM) and finishes at the dry end (5-9) just like the Fourdrinier machine ... 

Fourdrinier machine for paper 37 cylinders, 1.5 m diam velocity of paper = 4-5 m/s residence time 31 s heat transfer coefficient U = 0.34 kW/m °C. Water/solid = 0.4 2.8 g water evaporated/s m. ... 

The basic sheet-forming proeess on a Fourdrinier machine is as follows ... 

Dandy rolls, which are highly op>en, wire covered rolls used on fourdrinier machines ahead of the water line, for improvement of formation quality and for watermark application (Fig. 6.41). 

Modern fourdrinier machines are available up to a width of 360 inches and can operate at speeds up to 3000 ft/min. Newsprint machines are usually the widest and fastest, whereas those making heavier grades such as linerboard run somewhat more slowly. In the United States, there are several machines capable of producing over 1000 tons/day of linerboard. More specialized grades such as bond and printing papers are usually produced at a lower speed on narrower machines, and 150 to 250 tons/day would be considered a high output. Many specialized grades such as... 

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